Corrosion Behavior of Cold-Rolled and Solution-Treated Fe36Mn20Ni20Cr16Al5Si3 HEA in Different Acidic Solutions

Abstract

New high entropy alloys with good corrosion resistance in severe environment are receiving increasing attention. This work reports upon the microstructure and the corrosion resistance of the non-equiatomic Fe36Mn20Ni20Cr16Al5Si3 alloy in different acidic solutions. This alloy was designed by thermodynamic calculations using CALPHAD SOFTWARE, fabricated through casting, subjected to cold-rolling and solution-treatment, and compared with SS304 stainless steel. The corrosion test was performed through electrochemical behavior in 0.6 M NaCl and 0.6 M NaCl with 0.5 M H2SO4 and 0.6 M NaCl with 1 M H2SO4 solutions. Experimental results indicate that the alloy is composed of FCC phase as the main constituent besides a small amount of other BCC/B2 phases and other intermetallics. The corrosion test measurements revealed that cold-rolled Fe36Mn20Ni20Cr16Al5Si3 alloy is more resistant to corrosion in 0.6 M NaCl, while it is more susceptible to localized pits in H2SO4 to 0.6 M NaCl. Experimental results indicate that the pits are preferentially occurred in the areas of BCC/B2 phase precipitates. The solution-treated Fe36Mn20Ni20Cr16Al5Si3 HEA has the highest corrosion resistance compared to others with the addition of H2SO4 to 0.6 M NaCl. Surface morphologies of the different conditions were studied, and relevant results were reported.